Answer: A point B the potential energy is minimum.
Explanation :
A pendulum possesses two types of energy i.e. kinetic energy and potential energy.
At the highest point of the swing, the kinetic energy is equal to zero as it is not moving. At that point, it has only gravitational potential energy and it is given by :

h is the height
The gravitational potential energy decreases as it swings in a downwards direction.
So, B is the point where the potential energy is minimum and kinetic energy is maximum.
Hence the correct option is (B) " point B ".